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Specifications
Standard curve Not applicable
Recommended excitation1 20 µV (0.05 K to 0.1 K); 63 µV (0.1 K to 1 K); 10 mV or less for
T > 1 K
Dissipation at recommended excitation
10–13 W at 0.05 K, 10–7 W at 4.2 K (temperature and model dependent)
Thermal response time 200 ms at 4.2 K,
3 s at 77 K
Use in radiation Recommended for use in ionizing radiation environments – Click here for more information
Use in magnetic field Because of their strong magnetoresistance and associated orientation effect, germanium sensors are of very limited use in magnetic fields – Click here for more information |
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| Reproducibility |
|
Short term2 |
Long term3 |
| 4.2 K |
±0.5 mK |
±1 mK/yr |
| 77 K |
— |
±10 mK/yr |
1 Recommended excitation for T < 1 K based on Lake Shore calibration procedures using an AC resistance bridge – for more information refer to Appendix D and Appendix E
2 Short-term reproducibility data is obtained by subjecting sensor to repeated thermal shocks from 305 K to 4.2 K
3 Long-term stability data is obtained by subjecting sensor to 200 thermal shocks from 305 K to 77 K |
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Range of Use |
|
Minimum
limit |
Maximum
limit |
| GR-50-AA |
<0.05 K |
5 K |
| GR-300-AA |
0.3 K |
100 K |
| GR-1400-AA |
1.4 K |
100 K |
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Calibrated Accuracy |
|
Typical sensor accuracy4 |
|
GR-50 |
GR-300 |
GR-1400 |
| 0.05 K |
±5 mK |
— |
— |
| 0.3 K |
±5 mK |
±4 mK |
— |
| 0.5 K |
±5 mK |
±4 mK |
— |
| 1.4 K |
±6 mK |
±4 mK |
±4 mK |
| 4.2 K |
±6 mK |
±4 mK |
±4 mK |
| 77 K |
— |
±25 mK |
±15 mK |
| 100 K |
— |
±32 mK |
±18 mK |
|
4 [(Calibration uncertainty)2 + (reproducibility)2] 0.5 for more information see Appendices B, D, and E
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Typical Magnetic Field-Dependent Temperature Errors5 ΔT/T (%) at B (magnetic induction) |
| Germanium |
| T (K) |
2.5 T |
8 T |
14 T |
| 2.0 |
-8 |
-60 |
— |
| 4.2 |
-5 to -20 |
-30 to -55 |
-60 to -75 |
| 10 |
-4 to -15 |
-25 to -60 |
-60 to -75 |
| 20 |
-3 to -20 |
-15 to -35 |
-50 to -80 |
| 5 Long axis of thermometer parallel to applied field |
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Typical Resistance Values |
| GR-AA |
Typical resistance at 4.2 K |
Typical resistance range at 4.2 K |
| 50 |
30 Ω |
9 Ω to 65 Ω |
| 300 |
95 Ω |
15 Ω to 155 Ω |
| 1400 |
1750 Ω |
350 Ω to 6500 Ω |
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Temperature Response Data Table (typical)—See Appendix G for expanded response table |
|
GR-50-AA |
GR-300-AA |
GR-1400-AA |
| |
R(Ω) |
dR/dT
(Ω/K) |
(T/R)·
(dR/dT) |
R(Ω) |
dR/dT
(Ω/K) |
(T/R)·
(dR/dT) |
R(Ω) |
dR/dT
(Ω/K) |
(T/R)·
(dR/dT) |
| 0.05 K |
35000 |
-3642000 |
-5.203 |
— |
— |
— |
— |
— |
— |
| 0.1 K |
2320 |
-71860 |
-3.101 |
— |
— |
— |
— |
— |
— |
| 0.2 K |
364.6 |
-4043 |
-2.218 |
— |
— |
— |
— |
— |
— |
| 0.3 K |
164.0 |
-964.0 |
-1.763 |
35180 |
-512200 |
-4.367 |
— |
— |
— |
| 0.5 K |
73.75 |
-202.9 |
-1.376 |
5443 |
-34800 |
-3.197 |
— |
— |
— |
| 1.0 K |
33.55 |
-31.33 |
-0.9340 |
875.7 |
-1901 |
-2.170 |
— |
— |
— |
| 1.4 K |
24.73 |
-13.15 |
-0.7445 |
448.6 |
-581.3 |
-1.814 |
35890 |
-94790 |
-3.698 |
| 2.0 K |
19.32 |
-6.167 |
-0.6383 |
248.8 |
-187.4 |
-1.507 |
11040 |
-16670 |
-3.020 |
| 4.2 K |
13.66 |
-1.036 |
-0.3186 |
94.46 |
-26.56 |
-1.181 |
1689 |
-861.9 |
-2.144 |
| 10 K |
— |
— |
— |
33.20 |
-3.965 |
-1.194 |
252.8 |
-61.95 |
-2.451 |
| 40 K |
— |
— |
— |
7.789 |
-0.2351 |
-1.207 |
9.569 |
-0.4489 |
-1.876 |
| 77.4 K |
— |
— |
— |
3.504 |
-0.0496 |
-1.096 |
3.545 |
-0.0501 |
-1.093 |
| 100 K |
— |
— |
— |
2.716 |
-0.0238 |
-0.8754 |
2.796 |
-0.0208 |
-0.7441 |
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| Proper Selection of Germanium Sensors for Use Below 1 K |
|
| Germanium resistance thermometers are often classified according to their 4.2 K resistance value. However, for devices to be used below 1 K, there is no close correlation between the 4.2 K resistance and the suitability of the device as a thermometer. As a result, the Lake Shore low resistance germanium sensors (GR-50-AA and GR-300-AA) are classified according to their lowest useful temperatures, not their 4.2 K resistance values. |
| The resistance vs. temperature behavior for these devices is typical of all the germanium sensors. As the temperature is lowered, both the resistance and sensitivity (dR/dT) increase logarithmically. The lowest useful temperature is generally limited by the rapidly increasing resistance and the difficulties encountered in measuring high resistance values. |
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| The following recommendations are made concerning the optimum temperature range for using these devices: |
|
|
| GR-50-AA |
0.05 K to 1.0 K |
| GR-300-AA |
0.3 K to 100 K |
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| Increasingly better temperature resolution is achievable at lower temperatures. |
| In general, it is recommended you do not purchase a device which has a lower temperature limit than required, since some sensitivity (dR/dT) will be sacrificed at the higher temperatures. For example, a GR-300-AA will have more sensitivity at 1 K than a GR-50-AA. |
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Physical Specifications |
|
Mass |
Lead type |
Internal
atmosphere |
Sensor
materials |
GR-50-AA
GR-300-AA
GR-1400-AA |
395 mg |
4 color coded phosphor bronze with heavy build polyimide, attached with epoxy strain relief at sensor |
Helium 4 (4He) at =500 Ω, air at < 500 Ω |
Doped germanium chip mounted strain-free in a gold plated cylindrical copper can |
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